PLA was toughened by CSR, as was reflected by the significant increment in the impact strength by more than five times. The CSR-modified PLA possessed lower stiffness with reductions of both modulus and strength. Thus PLA/5wt% CSR was se selected as matrix for the production of WPC with rubber wood flour as reinforcement. With the presence of CSR in the PLA/rubber wood flour composites, the impact strength and the elongation at break of the composites improved significantly. Microscopic observation of the fracture surfaces of PBS/sawdust wood flour composites illustrated some wood particle breakage, remnant sites. The interfacial bonding was believed to have arisen from the formation of hydrogen bonding between the hydroxyl groups in the sawdust wood and the ester carbonyl group in the PBS.